Process for producing modified polymer modified polymer obtained by the process and rubber composition

ABSTRACT

Provided is a process for producing a modified polymer, characterized by carrying out primary modification in which a hydrocarbyloxysilane compound is reacted with the active site of a polymer having an active site of an organic metal type in a molecule and then carrying out secondary modification in which the hydrocarbyloxysilane compound is further reacted therewith. This makes it possible to provide a modified polymer which enhances interactions with silica and carbon black when used for both of silica-blended and carbon black-blended rubber compositions and which elevates the fracture characteristic, the abrasion resistance and the low heat buildup property at the same time and can exhibit a good workability.

TECHNICAL FIELD

The present invention relates to a process for producing a modifiedpolymer, a modified polymer obtained by the above process, a rubbercomposition and a pneumatic tire. More specifically, the presentinvention relates to a process for producing a modified polymer whichenhances interactions with silica and carbon black when used for both ofsilica-blended and carbon black-blended rubber compositions and whichelevates the fracture characteristic, the abrasion resistance and thelow heat buildup property at the same time and can exhibit a goodworkability, a modified polymer having the characteristics describedabove, which is obtained by the process described above, a rubbercomposition comprising the above modified polymer and a pneumatic tireprepared by using the above rubber composition.

BACKGROUND ART

In recent years, social request to energy saving is allowing requirementto a reduction in fuel consumption of cars to be severer. In order tomeet such requirement, a rolling resistance in tire performances isrequired to be reduced. A method for reducing a rolling resistance of atire by optimizing a tire structure has been investigated, but it iscarried out as the most usual method to use a material having a low heatbuildup property as a rubber composition.

In order to obtain such a rubber composition as having a low heatbuildup property, a large number of techniques for enhancing adispersibility of a filler used for a rubber composition has so far beendeveloped. Among them, particularly a method in which a polymerizableactive site of a diene base polymer obtained by anionic polymerizationusing a lithium compound is modified with a functional group havinginteraction with a filler is getting most popular.

Known as the most representative method among such methods are a methodin which carbon black is used as a filler and in which a polymerizableactive site is modified with a tin compound (Japanese Patent PublicationNo. 87630/1993) and a method in which carbon black is used in the samemanner and in which an amino group is introduced into a polymerizableactive end (Japanese Patent Application Laid-Open No. 207342/1987).

On the other hand, in recent years, requirements not only to a low fuelconsumption performance but also to a performance on a wet road surface(hereinafter referred to as a wet performance), particularly a brakingperformance has increased as concern about a safety of cars grows high.Accordingly, not only a mere reduction in a rolling resistance but alsoa high compatibility of a wet performance with a low fuel consumptionperformance are required to the performances of a rubber composition ina tire tread.

A method using silica in place of carbon black which has so far usuallybeen used as a reinforcing filler has already been carried out as amethod for obtaining a rubber composition providing a tire with such agood low fuel consumption and a good wet performance at the same time.

However, it has been apparent that when using silica as a reinforcingfiller, a fracture strength and an abrasion resistance characteristic ofa rubber composition can not be avoided from being notably reduced ascompared with carbon black. Further, silica is inferior indispersibility, and the workability in kneading has been a large problemin actually producing tires.

Accordingly, in order to obtain a rubber composition having a goodthermal property, not only carbon black or silica is used alone, butalso carbon black and silica are used in combination, and in additionthereto, required is an active site-modified polymer which has a wideinteraction with a variety of such fillers and which can provide thefillers with a good dispersibility and the rubber composition with anabrasion resistance.

However, it is the existing situation that since an active site-modifiedpolymer has so far been developed assuming that a single filler is used,active site-modified polymers having a satisfactory interaction withvarious fillers regardless of the kind of the fillers are restrictedvery much.

For example, the tin compound described above has a large dispersingeffect against carbon black but little dispersing effect against silica,and in addition thereto, it does not exhibit a reinforcing effect atall. Further, a dispersing effect of aminosilane against silica isreported in Japanese Patent Application Laid-Open No. 151275/1997, butthe effects thereof are not necessarily satisfactory.

On the other hand, disclosed is a method using alkoxysilane providingsilica with a dispersing effect and an effect for improving areinforcing property (Japanese Patent Application Laid-Open No.188501/1989, Japanese Patent Application Laid-Open No. 53513/1996 andJapanese Patent Application Laid-Open No. 53576/1996). However, it isapparent that since an alkoxysilyl group does not have at allinteraction with carbon black, no effects are expected when carbon blackis used as a reinforcing filler. Also, the same shall apply to otheractive site-modified polymers, and a method using, for example,aminoacrylamide is disclosed (Japanese Patent Application Laid-Open No.71687/1997 and Japanese Patent Application Laid-Open No. 208633/1997).However, while this method has an effect for improving a dispersibilityof silica to some extent, an effect for improving a dispersibility ofcarbon black is scarcely observed, and the problem that the hysteresisloss goes up is observed in the cases of a rubber composition of asystem in which carbon black and silica are used in combination and arubber composition in which carbon black is blended.

Further, disclosed is a modified polymer obtained by introducingalkoxysilane having a dialkylamino group into an active end of a polymerobtained by anionic polymerization using alkyllithium or lithiumamide asa polymerization initiator (Japanese Patent Publication No. 53763/1994and Japanese Patent Publication No. 57767/1994). When using thismodified polymer, obtained are a reinforcing property corresponding tosilica blended and a fixed dispersing effect to both silica and carbonblack as well as a good workability, but because of an amino group whichis a dialkyl group-substituted type having less effect to carbon black,particularly a blend system containing a large amount of carbon black isnot provided with a satisfactory effect as compared with a case where amodified polymer obtained by using a tin base modifying agent is used.

On the other hand, a polymer having an active site used in producing amodified polymer is obtained usually by anionically polymerizing aconjugated diene compound alone or a conjugated diene compound with anaromatic vinyl compound. It is not easy in terms of characteristics inanionic polymerization to introduce a functional group such as a primaryamino group and an organic onium base which are expected to be veryeffective for improving the physical properties into an active site ofthe above polymer obtained by anionic polymerization. Postpolymerization treatment under severe conditions and an expensiveprotective group are required, and therefore the industrial valuethereof is low.

In these methods, one functional group at most is introduced into anactive site of a polymer, and such complicated synthetic techniques asusing a dilithium base initiator and a macromonomer have to be used inorder to introduce a plurality of the functional groups described aboveper molecule of the polymer. Accordingly, they are not methods which areliable to be industrially applied. Further, in producing a rubbercomposition, the physical properties are tried to be improved bysubjecting the functional groups described above to heat mechanicaltreatment with a hydrocarbyl compound and a silane-modified polymer. Inthis case, the effects thereof are unsatisfactory, and in additionthereto, brought about are the problems that a valuable machine time ofa kneading machine is spent and that an evaporating amount of alcohol inthe kneading machine grows large. Thus, they are not methods which areindustrially preferred.

Under such circumstances, an object of the present invention is toprovide a process for producing a modified polymer which enhancesinteraction between silica and carbon black when used for both ofsilica-blended and carbon black-blended rubber compositions and whichelevates a fracture characteristic, an abrasion resistance and a lowheat buildup property at the same time and can exhibit a goodworkability, a modified polymer having the characteristics describedabove, which is obtained by the process described above, a rubbercomposition comprising the above modified polymer and a pneumatic tireprepared by using the above rubber composition.

DISCLOSURE OF THE INVENTION

Intensive researches repeated by the present inventors in order toachieve the object described above have resulted in finding that theabove object can be achieved by a modified polymer obtained by a methodin which a hydrocarbyloxysilane compound residue is first introducedinto the active site of a polymer having an active site and in whichthis hydrocarbyloxysilane compound residue is then condensed with ahydrocarbyloxysilane compound. The present invention has been completerbased on such knowledge.

That is, the present invention provides:

-   (1) a process for producing a modified polymer, characterized by    carrying out primary modification in which a hydrocarbyloxysilane    compound is reacted with the active site of a polymer having an    active site of an organic metal type in a molecule and then carrying    out secondary modification in which the hydrocarbyloxysilane    compound is further reacted therewith,-   (2) the process for producing a modified polymer as described in the    above item (1), wherein the polymer described above is obtained by    polymerizing a conjugated diene compound alone or a conjugated diene    compound with other monomers,-   (3) the process for producing a modified polymer as described in the    above item (1) or (2), wherein metal in the active site described    above is at least one selected from alkaline metals and alkaline    earth metals,-   (4) the process for producing a modified polymer as described in any    of the above items (1) to (3), wherein a condensation-accelerating    agent is added to the reaction system in the secondary modification,-   (5) A modified polymer obtained by the production process as    described in any of the above items (1) to (4),-   (6) a rubber composition comprising the modified polymer as    described in the above item (5),-   (7) the rubber composition as described in the above item (6)    comprising 100 parts by weight of (A) a rubber component containing    at least 30% by weight of the modified polymer as described in the    above item (5) and 10 to 100 parts by of (B) silica and/or carbon    black and-   (8) a pneumatic tire characterized by using the rubber composition    as described in the above item (6) or (7).

THE MOST PREFERRED EMBODIMENT CARRYING OUT THE INVENTION

First, the production process for a modified polymer according to thepresent invention shall be explained.

In the production process for a modified polymer according to thepresent invention, carried out is primary modification in which ahydrocarbyloxysilane compound is introduced into the active site of apolymer having an active site of an organic metal type in a molecule,and then secondary modification in which the hydrocarbyloxysilanecompound is further reacted therewith is carried out. These primarymodification and secondary modification make it possible to introducethe hydrocarbyloxysilane compound residue into the active site describedabove in an amount of more than the equivalent.

The production process for a polymer having an active site of an organicmetal type shall not specifically be restricted, and all of a solutionpolymerization method, a gas phase polymerization method and a bulkpolymerization method can be used. In particular, the solutionpolymerization method is preferred. The polymerization form may be anyof a batch system and a continuous system.

The metal in the active site described above is preferably one selectedfrom alkaline metals and alkaline earth metals, and lithium metal isparticularly preferred.

In the solution polymerization method described above, the targetedpolymer is obtained, for example, by anionically polymerizing aconjugated diene compound alone or a conjugated diene compound with anaromatic vinyl compound using a lithium compound as a polymerizationinitiator.

Further, it is effective as well to activate a halogen atom contained inthe polymer by an organic metal compound in the presence of ahalogen-containing monomer. For example, it is effective as well tosubject a bromine part of a copolymer containing an isobutylene unit, aparamethylstylene unit and a parabromomethylstylene unit to lithiationto convert it to an active site.

The active site described above may be merely present in a molecule ofthe polymer and shall not specifically be restricted. When the polymeris prepared by anionic polymerization using an alkaline metal compoundand/or an alkaline earth metal compound as a polymerization initiator,the active site described above is located usually at an end of thepolymer.

The conjugated diene compound described above includes, for example,1,3-butadiene; isoprene; 1,3-pentadiene; 2,3-dimethylbutadiene;2-phenyl-1,3-butadiene; and 1,3-hexadiene. They may be used alone or incombination of two or more kinds thereof, and among them, 1,3-butadieneand isoprene are particularly preferred.

The aromatic vinyl compound used for copolymerization with theseconjugated diene compounds includes, for example, styrene;α-methylstyrene; 1-vinylnaphthalene; 3-vinyltoluene; ethylvinylbenzene;divinylbenzene; 4-cyclohexylbenzene; and 2,4,6-trimethylstyrene. Theymay be used alone or in combination of two or more kinds thereof, andamong them, styrene is particularly preferred.

Further, when the conjugated diene compound and the aromatic vinylcompound are used as monomers to carry out copolymerization,1,3-butadiene and styrene are particularly suitably used since they areexcellent in terms of practicality such as an easiness in obtaining themonomers and an anionic polymerization characteristic which is a livingproperty.

When the solution polymerization method is used, the monomerconcentration in a solvent is preferably 5 to 50% by weight, morepreferably 10 to 30% by weight. When the conjugated diene compound andthe aromatic vinyl compound are used to carry out copolymerization, thearomatic vinyl compound contained in the charged monomer mixture has acontent falling in a range of preferably 3 to 50% by weight, morepreferably 5 to 45% by weight.

The lithium compound of the polymerization initiator shall notspecifically be restricted, and hydrocarbyllithium and a lithium amidecompound are preferably used. When hydrocarbyllithium of the former isused, obtained is a conjugated diene base polymer which has ahydrocarbyl group at a polymerization-initiating end and in which theother end is a polymerization active site. When the lithiumamidecompound of the latter is used, obtained is a conjugated diene basepolymer which has a nitrogen-containing group at apolymerization-initiating end and in which the other end is apolymerization active site.

The hydrocarbyllithium described above is preferably a compound having ahydrocarbyl group having 2 to 20 carbon atoms and includes, for example,ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium,sec-butyllithium, tert-octyllithium, n-decyllithium, phenyllithium,2-naphthyllithium, 2-butylphenyllithium, 4-phenyl-butyllithium,cyclohexyllithium, cyclopentyllithium and reaction products ofdiisopropenylbenzene with butyllithium. Among them, n-butyllithium ispreferred.

On the other hand, the lithium amide compound includes, for example,lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide,lithium heptamethyleneimide, lithium dodecamethyleneimide, lithiumdimethylamide, lithium diethylamide, lithium dibutylamide, lithiumdipropylamide, lithium diheptylamide, lithium dihexylamide, lithiumdioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide,lithium N-methylpiperazide, lithium ethylpropylamide, lithiumethylbutylamide, lithium methylbutylamide, lithium ethylbenzylamide andlithium methylphenethylamide. Among them, cyclic lithium amides such aslithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide,lithium heptamethyleneimide and lithium dodecamethyleneimide arepreferred in terms of an interaction effect against carbon black and apolymerization initiating ability, and lithium hexamethyleneimide andlithium pyrrolidide are particularly suited.

In these lithium amide compounds, usually the compounds prepared inadvance from secondary amines and lithium compounds are used forpolymerization in many cases, and they can be prepared as well in thepolymerization system (in-situ). A use amount of the abovepolymerization initiator is selected in a range of preferably 0.2 to 20millimole per 100 g of the monomer.

The process for producing the conjugated diene base polymer by anionicpolymerization using the lithium compounds described above as apolymerization initiator shall not specifically be restricted, andconventionally known methods can be used.

To be specific, the targeted conjugated diene base polymer is obtainedby anionically polymerizing the conjugated diene compound or theconjugated diene compound with the aromatic vinyl compound using thelithium compound described above as a polymerization initiator in thepresence of a randomizer used if desired in an organic solvent which isinactive to the reaction, for example, a hydrocarbon base solvent suchas aliphatic, alicyclic and aromatic hydrocarbon compounds.

The hydrocarbon base solvent described above is preferably a solventhaving 3 to 8 carbon atoms, and capable of being given are, for example,propane, n-butane, isobutane, n-pentane, isopentane, n-hexane,cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis-2-butene,1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene andethylbenzene. They may be used alone or in a mixture of two or morekinds thereof.

The randomizer used if desired is a compound having actions such ascontrolling of a micro structure in the conjugated diene polymer, forexample, an increase in a 1,2-bond of a butadiene part in abutadiene-styrene copolymer and a 3,4-bond in an isoprene polymer andcontrolling of a composition distribution of a monomer unit in aconjugated diene compound-aromatic vinyl compound copolymer, forexample, a randomization in a butadiene unit and a styrene unit in abutadiene-styrene copolymer. This randomizer shall not specifically berestricted, and optional compounds can suitably be selected frompublicly known compounds which have so far usually been used asrandomizer and used. To be specific, capable of being given are ethersand primary amines such as dimethoxybenzene, tetrahydrofuran,dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycoldimethyl ether, bistetrahydrofurylpropane, triethylamine, pyridine,N-methylmorpholine, N,N,N′,N′-tetramethylethylenediamine and1,2-piperidinoethane. Further, potassium salts such as potassiumt-amylate and potassium t-butoxide and sodium salts such as sodiumt-amylate can be used as well.

These randomizers may be used alone or in combination of two or morekinds thereof. A use amount thereof is selected preferably in a range of0.01 to 1000 mole equivalent per mole of the lithium compound.

Temperature in this polymerization reaction is selected in a range ofpreferably 0 to 150° C., more preferably 20 to 130° C. Thepolymerization reaction can be carried out under generated pressure, andusually it is carried out preferably at pressure which is enough tomaintain the monomer substantially to a liquid phase. That is, thehigher pressure can be used if desired, though depending on theindividual substances to be polymerized, the polymerizing solvent usedand the polymerizing temperature, and such pressure can be obtained by asuitable method such as applying pressure to a reactor by gas which isinert to the polymerization reaction.

In this polymerization, all the raw materials taking part in thepolymerization such as the polymerization initiator, the solvent, themonomers and the like are used preferably after removing reactioninhibiting substances such as water, oxygen, carbon dioxide and proticcompounds.

When the polymer is obtained in the form of an elastomer, the resultingpolymer or copolymer has preferably a glass transition point (Tg) of −90to −15° C. which is determined by a differential thermal analyticalmethod. It is difficult to obtain the polymer having a glass transitionpoint of lower than −90° C. If it exceeds −15° C., the viscosity growstoo high in a room temperature region, and handling is difficult in acertain case.

In the present invention, used is a method in which thehydrocarbyloxysilane compound I for the primary modification is added tothe polymer thus obtained having an active site of an organic metal typein a molecule in an amount of preferably 0.5 mole equivalent or more ofthe apparent active site based on the above active site (usually, onemole of the above hydrocarbyloxysilane compound I for the primarymodification corresponds to several mole equivalents of the active site)to react almost equivalent of the hydrocarbyloxysilane compound I basedon the above active site to introduce the hydrocarbyloxysilane compoundresidue into almost all of the above active sites and in which thehydrocarbyloxysilane compound II for the secondary modification is thenadded to the reaction system to condense the hydrocarbyloxysilanecompound residue introduced into the above active site with thehydrocarbyloxysilane compound II or the above residue with the unreactedhydrocarbyloxysilane compound I.

In the polymer used in the above modification reaction, at least 20% ofthe polymer chain preferably has the above active site.

In the modifying method described above, capable of being used as thehydrocarbyloxysilane compound I for the primary modification which isused for reacting with the active site of the polymer are ahydrocarbyloxysilane compound represented by Formula (I):

(wherein A¹ represents a monovalent group having at least one functionalgroup selected from (thio)epoxy, (thio)isocyanate, (thio)ketone,(thio)aldehyde, cyan, pyridine, imine, amide, isocyanuric acidtriesters, hydrocarbyl (thio)carboxylate, metal salts of(thio)carboxylic acid esters, carboxylic anhydride, carboxylic halidesand dihydrocarbyl ester carbonate; R¹ represents a single bond or adivalent inert hydrocarbon group; R² and R³ each represent independentlya monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms ora monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms; nis an integer of 0 to 2, and when a plurality of OR³ is present, aplurality of OR³ may be the same as or different from each other; and anactive proton and an onium salt are not contained in the molecule)and/or a partially condensed product thereof. In this case, thepartially condensed product means a compound in which a part (not thewhole) of SiOR of the hydrocarbyloxysilane compound is combined viaSiOSi by condensation.

In Formula (I) described above, among the functional groups in A¹, imineincludes ketimine, aldimine and amidine, and (thio)carboxylates includeunsaturated carboxylates such as acrylate and methacrylate. Alkalinemetals, alkaline earth metals, Al, Sn and Zn can be given as metals inthe metal salts of (thio)carboxylates.

An alkylene group having 1 to 20 carbon atoms can preferably be given asthe divalent inactive hydrocarbon group represented by R¹. This alkylenegroup may be linear, branched or cyclic, and the linear group isparticularly suited. The examples of the above linear alkylene groupinclude methylene, ethylene, trimethylene, tetramethylene,pentamethylene, hexamethylene, octamethylene, decamethylene anddodecamethylene.

Capable of being given as R² and R³ are an alkyl group having 1 to 20carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an arylgroup having 6 to 18 carbon atoms and an aralkyl group having 7 to 18carbon atoms. In this case, the alkyl group and the alkenyl group eachdescribed above may be linear, branched or cyclic, and the examplesthereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,sec-butyl, tert-butyl, pentyl, hexyl, octyl, decyl, dodecyl,cyclopentyl, cyclohexyl, vinyl, propenyl, allyl, hexenyl, octenyl,cyclopentenyl and cyclohexenyl.

The above aryl group may have a substituent such as a lower alkyl groupon an aromatic ring, and the examples thereof include phenyl, tolyl,xylyl and naphthyl. Further, the above aralkyl group may have asubstituent such as a lower alkyl group on an aromatic ring, and theexamples thereof include benzyl, phenethyl and naphthylmethyl.

The term n is an integer of 0 to 2, preferably 0, and an active protonand an onium salt do not have to be contained in this molecule.

Capable of being preferably given as the hydrocarbyloxysilane compoundrepresented by the above Formula (I) are, for example, (thio)epoxygroup-containing hydrocarbyloxysilane compounds such as2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane,(2-glycidoxyethyl)methyldimethoxysilane,3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane,(3-glycidoxypropyl)methyldimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and2-(3,4-epoxycyclohexyl)ethyl(methyl)dimethoxysilane, and compoundsobtained by substituting the epoxy groups in these compounds with athioepoxy group. Among them, 3-glycidoxypropyltrimethoxysilane and3-glycidoxypropyltriethoxysilane are particularly suited.

Capable of being preferably given as the imine group-containinghydrocarbyloxysilane compound areN-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propaneamine,N-(1-methylethylidene)-3-(triethoxysilyl)-1-propaneamine,N-ethylidene-3-(triethoxysilyl)-1-propaneamine,N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propaneamine,N-(4-N,N-dimethylaminobenzylidene)-3-(triethoxysilyl)-1-propaneamine,N-(cyclohexylidene)-3-(triethoxysilyl)-1-propaneamine andtrimethoxysilyl compounds, methyldiethoxysilyl compounds,ethyldiethoxysilyl compounds, methyldimethoxysilyl compounds andethyldimethoxysilyl compounds each corresponding to the abovetriethoxysilyl compounds. Among them, particularly suited areN-(1-methylpropylidene)-3-(triethoxysilyl)-1-propaneamine andN-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propaneamine. Anotherexamples of the imine (amidine) group-containing compound include1-[3-(triethoxysilyl)propyl]-4,5-dihydroimidazole,1-[3-(trimethoxysilyl)propyl]-4,5-dihydroimidazole,N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole,N-(3-isopropoxylsilylpropyl)-4,5-dihydroimidazole andN-(3-methyldiethoxysilylpropyl)-4,5-dihydroimidazole. Among them,N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole is preferred.

Further, the other hydrocarbyloxysilane compounds include carboxylategroup-containing compounds. To be specific, they include3-methacryloyloxypropyltriethoxysilane,3-methacryloyloxypropyltrimethoxysilane,3-methacryloyloxypropylmethyldiethoxysilane and3-methacryloyloxypropyltriisopropoxysilane. Among them,3-methacryloyloxypropyltrimethoxysilane is preferred.

Also, the hydrocarbyloxysilane compound includes isocyanategroup-containing hydrocarbyloxysilane compounds. To be specific, theyinclude 3-isocyanatopropyltrimethoxysilane,3-isocyanatopropyltriethoxysilane,3-isocyanatopropylmethyldiethoxysilane and3-isocyanatopropyltriisopropoxysilane. Among them,3-isocyanatopropyltriethoxysilane is preferred.

Further, the hydrocarbyloxysilane compound includes carboxylic anhydridegroup-containing compounds. To be specific, they include3-triethoxysilylpropylsuccinic anhydride,3-trimethoxysilylpropylsuccinic anhydride and3-methyldiethoxysilylpropylsuccinic anhydride. Among them,3-triethoxysilylpropylsuccinic anhydride is preferred.

Further, 2-cyanoethyltriethoxysilane and 2-trimethoxysilylpyridine canbe given as the other hydrocarbyloxysilane compounds.

These hydrocarbyloxysilane compounds (I) may be used alone or incombination of two or more kinds thereof.

Next, in the modifying method described above, capable of being used asthe hydrocarbyloxysilane compound I for the primary modification whichis used for reacting with the active site of the polymer are, forexample, a hydrocarbyloxysilane compound represented by Formula (II):

(wherein A² represents a monovalent group having at least one functionalgroup selected from cyclic tertiary amine, non-cyclic tertiary amine,pyridine, cyan, sulfide and multisulfide; R⁴ represents a single bond ora divalent inert hydrocarbon group; R⁵ and R⁶ each representindependently a monovalent aliphatic hydrocarbon group having 1 to 20carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18carbon atoms; m is an integer of 0 to 2, and when a plurality of OR⁶ ispresent, a plurality of OR⁶ may be the same as or different from eachother; and an active proton and an onium salt are not contained in themolecule) and/or a partially condensed product thereof In this case, thepartially condensed product means the same one as described in Formula(I).

In Formula (II) described above, the non-cyclic tertiary aminerepresented by A² includes N,N-disubstituted aromatic amines such asN,N-disubstituted aniline, and the cyclic tertiary amine can contain a(thio)ether bond as a part of the ring. The divalent inactivehydrocarbon group represented by R⁴ and R⁵ and R⁶ are the same asexplained in R¹, R² and R³ in Formula (I). An active proton and an oniumsalt do not have to be contained in the molecule.

Capable of being given as the hydrocarbyloxysilane compound representedby the above Formula (II) are, for example, non-cyclic tertiary aminegroup-containing hydrocarbyloxysilane compounds such as3-dimethylaminopropyl(triethoxy)silane,3-dimethylaminopropyl(trimethoxy)silane,3-diethylaminopropyl(triethoxy)silane,3-diethylaminopropyl(trimethoxy)silane,2-dimethylaminoethyl(triethoxy)silane,2-dimethylaminoethyl(trimethoxy)silane,3-dimethylaminopropyl(diethoxy)methylsilane and3-dibutylaminopropyl(triethoxy)silane. Among them,3-dimethylaminopropyl(triethoxy)silane and3-dimethylaminopropyl(trimethoxy)silane are suited.

Capable of being given as the cyclic tertiary amine group-containinghydrocarbyloxysilane compounds are, for example,3-(1-hexamethyleneimino)propyl(triethoxy)silane,3-(1-hexamethyleneimino)propyl(trimethoxy)silane,(1-hexamethyleneimino)methyl(trimethoxy)silane,(1-hexamethyleneimino)methyl(triethoxy)silane,2-(1-hexamethyleneimino)ethyl(triethoxy)silane,2-(1-hexamethyleneimino)ethyl(trimethoxy)silane,3-(1-pyrrolidinyl)propyl(triethoxy)silane,3-(1-pyrrolidinyl)propyl(trimethoxy)silane,3-(1-heptamethyleneimino)propyl(triethoxy)silane,3-(1-dodecamethyleneimino)propyl(triethoxy)silane,3-(1-hexamethyleneimino)propyl(diethoxy)methylsilane,3-(1-hexamethyleneimino)propyl(diethoxy)ethylsilane and3-[10-(triethoxysilyl)decyl]-4-oxazoline. Among them,3-(1-hexamethyleneimino)propyl(triethoxy)silane and(1-hexamethyleneimino)methyl(trimethoxy)silane can preferably be given.In particular, 3-(1-hexamethyleneimino)propyl(triethoxy)silane issuited.

Further, capable of being given as the other hydrocarbyloxysilanecompounds are 2-(trimethoxysilylethyl)pyridine,2-(triethoxysilylethyl)pyridine and 2-cyanoethyltriethoxysilane.

These hydrocarbyloxysilane compounds (II) may be used alone or incombination of two or more kinds thereof.

In the modifying method described above, capable of being used as thehydrocarbyloxysilane compound I for the primary modification which isused for reacting with the active site of the polymer are, for example,a hydrocarbyloxysilane compound represented by Formula (III):R⁷ _(p)—Si—(OR⁸)_(4-p)  (III)(wherein R⁷ and R⁸ each represent independently a monovalent aliphatichydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatichydrocarbon group having 6 to 18 carbon atoms; p is an integer of 0 to2, and when a plurality of OR⁸ is present, a plurality of OR⁸ may be thesame as or different from each other; and an active proton and an oniumsalt are not contained in the molecule) and/or a partially condensedproduct thereof In this case, the partially condensed product means thesame one as described in Formula (I).

In Formula (III) described above, R⁷ and R⁸ are the same as explained inR² and R³ in Formula (I) described above.

Capable of being preferably given as the hydrocarbyloxysilane compoundrepresented by the above Formula (III) are, for example,tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane,tetraisopropoxysilane, tetra-n-butoxysilane, tetraisobutoxysilane,tetra-sec-butoxysilane, tetra-tert-butoxysilane, methyltrimethoxysilane,methyltriethoxysilane, methyltripropoxysilane,methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane,propyltriethoxysilane, butyltrimethoxysilane, phenyltrimethoxysilane,phenyltriethoxysilane, dimethyldimetoxysilane,methylphenyldimethoxysilane, vinyltrimethoxysilane,vinyltriethoxysilane, divinyldimethoxysilane and divinyldiethoxysilane.Among them, tetraethoxysilane is particularly suited.

These hydrocarbyloxysilane compounds (III) may be used alone or incombination of two or more kinds thereof.

In this primary modification, the optional mixtures of thehydrocarbyloxysilane compounds represented by Formulas (I), (II) and(III) can be used as the hydrocarbyloxysilane compound I for the primarymodification which is used for reaction with the active site of thepolymer.

In the modifying method of the present invention, the secondarymodification is carried out subsequently to the primary modification. Inthis modifying method, the polymer having an active site is firstreacted with the hydrocarbyloxysilane compound I added to introduce thehydrocarbyloxysilane compound residue into the above active site, andthen carried out is the secondary modification in which thehydrocarbyloxysilane compound II newly added for the secondarymodification or the unreacted hydrocarbyloxysilane compound remaining inthe reaction system is condensed with the hydrocarbyloxysilane compoundresidue introduced into the active site.

Capable of being used as the hydrocarbyloxysilane compound II for thesecondary modification is at least one selected from thehydrocarbyloxysilane compound represented by Formula (I) described aboveand/or the partially condensed product thereof, the hydrocarbyloxysilanecompound represented by Formula (II) described above and/or thepartially condensed product thereof and a hydrocarbyloxysilane compoundrepresented by Formula (IV):

(wherein A³ represents a monovalent group having at least one functionalgroup selected from alcohol, thiol, amide, primary amine or an oniumsalt thereof, cyclic secondary amine or an onium salt thereof,non-cyclic secondary amine or an onium salt thereof, cyclic tertiaryamine or an onium salt thereof, non-cyclic tertiary amine or an oniumsalt thereof, a group having an aryl or benzyl Sn bond, sulfonyl,sulfinyl and nitrile; R⁹ represents a single bond or a divalent inerthydrocarbon group; R¹⁰ and R¹¹ each represent independently a monovalentaliphatic hydrocarbon group having 1 to 20 carbon atoms or a monovalentaromatic hydrocarbon group having 6 to 18 carbon atoms; q is an integerof 0 to 2, and when a plurality of OR¹¹ is present, a plurality of OR¹¹may be the same as or different from each other) and/or a partiallycondensed product thereof.

In Formula (IV) described above, the primary amine represented by A³includes aromatic amines such as aniline, and the non-cyclic secondaryamine includes N-monosubstituted aromatic amines such asN-monosubstituted aniline. Further, the non-cyclic tertiary amine or theonium salt thereof includes N,N-disubstituted aromatic amines such asN,N-disubstituted aniline or onium salts thereof. In the case of thecyclic secondary amine and the cyclic tertiary amine, a (thio)ether bondcan be contained therein as a part of the ring. The divalent inactivehydrocarbon group represented by R⁹ and R¹⁰ and R¹¹ are the same asexplained in R¹, R² and R³ in Formula (I) described above.

Capable of being preferably given as the hydrocarbyloxysilane compoundrepresented by the above Formula (IV) are, for example,3-aminopropyl-trimethoxysilane, 3-aminopropyltriethoxysilane,hydroxymethyltrimethoxysilane, hydroxymethyltriethoxysilane,mercaptomethyltrimethoxysilane, mercaptomethyltriethoxysilane,aminophenyl-trimethoxysilane, aminophenyltriethoxysilane,3-(N-methylamino)propyltrimethoxysilane,3-(N-methylamino)propyltriethoxysilane,octadecyldimethyl-(3-trimethylsilylpropyl)ammonium chloride,octadecyldimethyl(3-triethylsilylpropyl)ammonium chloride,cyanomethyltrimethoxysilane, cyanomethyl-triethoxysilane,sulfonylmethyltrimethoxysilane, sulfonylmethyltriethoxysilane,sulfinylmethyl-trimethoxysilane, sulfinylmethyltriethoxysilane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and2-(6-aminohexyl)aminopropyltrimethoxysilane.

These hydrocarbyloxysilane compounds II may be used alone or incombination of two or more kinds thereof.

An addition timing of the hydrocarbyloxysilane compound II for thesecondary modification is usually after the primary modification, andthe hydrocarbyloxysilane compounds represented by Formulas (I), (II) and(III) and/or the partially condensed products thereof may be added atthe same time as the hydrocarbyloxysilane compound I for the primarymodification. For example, when modifying the polymer having an activesite of an organic metal type in a molecule with thehydrocarbyloxysilane compounds represented by Formulas (I) and (III),the compound represented by Formula (I) is reacted preferentially withthe above active site and functions as the hydrocarbyloxysilane compoundI for the primary modification. On the other hand, if acondensation-accelerating agent described later is added after theprimary modification, the hydrocarbyloxysilane compounds represented byFormula (III) described above and the unreacted hydrocarbyloxysilanecompound represented by Formula (I) described above function as thehydrocarbyloxysilane compound II for the secondary modification.

In the secondary modification, it is included as well in the scope ofthe present invention that the residue of the hydrocarbyloxysilanecompound I described above introduced into the active site of thepolymer is condensed with the unreacted hydrocarbyloxysilane compoundadded as the hydrocarbyloxysilane compound I to thereby introduce thehydrocarbyloxysilane compound residue into the above active site in anamount of larger than an equivalent.

This is readily achieved, for example, by adding acondensation-accelerating agent described later after the primarymodification to condense the hydrocarbyloxysilane compound residueintroduced into the active site of the polymer with the unreactedhydrocarbyloxysilane compound I. The hydrocarbyloxysilane compoundsrepresented by Formulas (I) and (II) and/or the partially condensedproducts thereof are suitably used as the hydrocarbyloxysilane compoundused in this case, and they can be used alone or in a mixture. In theabove embodiment, the secondary modification goes on without adding thehydrocarbyloxysilane compound II for the secondary modification afterthe primary modification, and the hydrocarbyloxysilane compound II forthe secondary modification may be added together with thecondensation-accelerating agent after the primary modification.

In the modification reaction described above in the present invention(meaning the primary modification and the secondary modification),either of solution reaction and solid phase reaction can be used, andthe solution reaction (allowed to contain the unreacted monomers used inthe polymerization) is suited. The mode of this modification reactionshall not specifically be restricted, and it may be carried out by meansof a batch type reactor or may be carried out by a continuous systemusing an apparatus such as a multistage continuous reactor and an inlinemixer. It is important to carry out the above modification reactionbefore carrying out desolvent treatment, water treatment and heattreatment after finishing the polymerization reaction.

The modification reaction is carried out preferably at a temperature of20° C. or higher. The polymerizing temperature of the conjugated dienebase polymer can be used as it is, and more preferred range thereofincludes 30 to 120° C. If the reaction temperature is lowered, shown aretendencies such as too much rise in a viscosity of the polymer, adeterioration in a dispersibility of the reaction product and a delay ina reaction rate in the secondary modification reaction. On the otherhand, if the reaction temperature is elevated, the polymerizing activesite tends to be liable to be deactivated.

In this modification reaction, the hydrocarbyloxysilane compound residueintroduced into the active site of the polymer is condensed with thehydrocarbyloxysilane compound II or the unreacted hydrocarbyloxysilanecompound I preferably in the presence of the condensation-acceleratingagent. A combination of a metal compound known as a curing catalyst foralkoxy condensation curing type cold cross-linking (RTV) silicon andwater can usually be used as the above condensation-accelerating agent,and a combination of carboxylate of tin and/or titanium alkoxide andwater can preferably be given. Water may be added to the reaction systemin the form of a solution of an organic solvent such as alcohol which iscompatible with water or may be add and dispersed directly in ahydrocarbon solution using various chemical engineering methods.

The metal compound used as the condensation-accelerating agent ispreferably a tin compound having an oxidation number of 2 represented bythe following Formula (V):S_(n)(OCOR¹²)₂  (V)(wherein R¹² represents an alkyl group having 2 to 19 carbon atoms), atin compound having an oxidation number of 4 represented by thefollowing Formula (VI):R¹³ _(x)SnA⁴ _(y)B¹ _(4-y-x)  (VI)(wherein R¹³ represents an aliphatic hydrocarbon group having 1 to 30carbon atoms; x is an integer of 1 to 3, and y is 1 or 2; A⁴ representsa group selected from a carboxyl group having 2 to 30 carbon atoms, anα,γ-dionyl group having 5 to 20 carbon atoms, a hydrocarbyloxy grouphaving 3 to 20 carbon atoms and a siloxy group which is tri-substitutewith a hydrocarbyl group having 1 to 20 carbon atoms and/or ahydrocarbyloxy group having 1 to 20 carbon atoms; and B¹ represents ahydroxyl group or halogen) and a titanium compound represented by thefollowing Formula (VII):A⁵ _(z)TiB² _(4-z)  (VII)(wherein A⁵ represents a group selected from an alkoxy group having 3 to20 carbon atoms and a siloxy group which is tri-substitute with an alkylgroup having 1 to 20 carbon atoms and/or an alkoxy group having 1 to 20carbon atoms; B² represents an α, γ-dionyl group having 5 to 20 carbonatoms; and z is 2 or 4).

To be more specific, capable of being suitably used are dicarboxylatesof divalent tin, dicarboxylates of tetravalent dihydrocarbyltin(including bis(hydrocarbyldicarboxylic acid) salts),bis(α,γ-diketonate), alkoxy halide, monocarboxylate hydroxide,alkoxy(trihydrocarbyl siloxide), alkoxy(dihydrocarbyl alkoxysiloxide),bis(trihydrocarbyl siloxide) and bis(dihydrocarbyl alkoxysiloxide). Thehydrocarbyl group bonded to tin has preferably 4 or more carbon atoms,particularly preferably 4 to 8 carbon atoms.

The titanium compound described above includes tetraalkoxide of titaniumhaving an oxidation number of 4, dialkoxybis(α,γ-diketonate) andtetrakis(trihydrocarbioxide), and particularlytetrakis(trihydrocarbioxide) is suitably used.

Water is suitably used as it is or in the form of a solution of alcoholand the like or a micelle dispersed in a hydrocarbon solvent, and inaddition thereto, capable of being effectively used as well, ifnecessary, is a moisture potentially contained in compounds which canrelease water in a reaction system, such as water adsorbed on a solidmatter surface and hydrated water contained in a hydrate. Accordingly,it is given as the preferred embodiment as well to use a compound whichcan readily release water such as a solid matter having adsorbed waterand a hydrate in combination with the metal compound described above.

These two components constituting the condensation-accelerating agentmay be added separately to the reaction system or may be mixedimmediately before use and added in the form of a mixture, but it is notpreferred to store the mixture for a long period of time since the metalcompound is decomposed.

A use amount of the above condensation-accelerating agent is preferablyselected so that both mole ratios of metal and a proton source in themetal compound described above based on the whole amount of thehydrocarbyloxysilyl bond present in the system are 0.1 or more.

Both mole numbers of metal contained in the metal compound describedabove and water which is effective for the reaction are preferably 0.1or more in terms of a mole ratio based on the whole amount of thehydrocarbyloxysilyl group present in the system. The upper limit thereofis varied according to the purposes and the reaction conditions, andpreferably present is 0.5 to 3 mole equivalent of effective water basedon an amount of the hydrocarbyloxysilyl group bonded to the active siteof the polymer at a stage before the condensation treatment.

In the present invention, publicly known antioxidants and short stoppingagents for the purpose of terminating the polymerization reaction can beadded, if desired, in a step after introducing the hydrocarbyloxysilanecompound residue into the active site in the modification reaction.Further, a condensation-inhibiting agent such as higher carboxylic acidesters of polyhydric alcohols may be added to the reaction system afterfinishing the modification reaction.

Conventionally known after-treatments such as desolvent are carried outafter finishing the modification treatment in the manner describedabove, and thus the targeted modified polymer can be obtained. Apolymerization chain active site-modified group of the above polymer canbe analyzed by means of a high performance liquid chromatography (HPLC)and a nuclear magnetic resonance spectroscopy (NMR).

The above modified polymer has a Mooney viscosity (ML₁₊₄, 100° C.) ofpreferably 10 to 150, more preferably 15 to 70. If the Mooney viscosityis less than 10, the rubber physical properties including the fracturecharacteristic are not sufficiently obtained. On the other hand, if itexceeds 150, the workability is deteriorated, and it is difficult to mixthe polymer with the blending components.

The present invention provides as well the modified polymer obtained inthe manner described above.

When the modified polymer of the present invention is used as a rubbercomponent in silica-blended and carbon black-blended rubbercompositions, it can raise the interaction against both of silica andcarbon black, elevate the rapture characteristic, the abrasionresistance and the low heat buildup property at the same time andexhibit the good workability.

The rubber composition of the present invention contains the modifiedpolymer obtained by the process described above, and usually used is thecomposition comprising 100 parts by weight of (A) a rubber componentcontaining at least 30% by weight of the above modified polymer and 10to 100 parts by of (B) silica and/or carbon black.

In the rubber composition of the present invention, at least 30% byweight of the modified polymer described above is preferably containedas the rubber component of the component (A). If this amount is lessthan 30% by weight, the rubber composition having desired physicalproperties is less liable to be obtained, and the objects of the presentinvention are not achieved in a certain case. The modified polymercontained in the rubber component has a content of more preferably 35%by weight or more, particularly suitably 40 to 100% by weight.

The above modified polymers may be used alone or in combination of twoor more kinds thereof. The rubber component used in combination with theabove modified polymer includes natural rubber and diene base syntheticrubber, and the diene base synthetic rubber includes, for example,styrene-butadiene copolymers (SBR), polybutadiene (BR), polyisoprene(IR), butyl rubber (IIR), ethylene-propylene copolymers and mixturesthereof Further, it may be a compound partially provided with a branchedstructure by using a multifunctional modifying agent, for example, amodifying agent such as tin tetrachloride.

In the rubber composition of the present invention, silica and/or carbonblack are preferably used as a reinforcing filer of the component (B).

The silica described above shall not specifically be restricted, and itcan optionally be selected from compounds which have so farconventionally been used as a reinforcing filler for rubber.

The above silica includes, for example, wet silica (hydrous silicicacid), dry silica (anhydrous silicic acid), calcium silicate andaluminum silicate, and among them, preferred is wet silica in which aneffect for improving the rapture characteristic and a compatible effectwith the wet gripping property are the most notable. On the other hand,carbon black shall not specifically be restricted, and it can optionallybe selected from compounds which have so far conventionally been used asa reinforcing filler for rubber. This carbon black includes, forexample, FEF, SRF, HAF, ISAF and SAF. Preferred is carbon black havingan iodine adsorption number (IA) of 60 mg/g or more and a dibutylphthalate absorption (DBP) of 80 ml/100 g or more. An effect forimproving various physical properties is increased by using the abovecarbon black, and HAF, ISAF and SAF which are excellent in an abrasionresistance are particularly preferred.

A blending amount of the reinforcing filer of the above component (B) ispreferably 10 to 100 parts by weight per 100 parts by weight of therubber component of the component (A). If a blending amount of thereinforcing filer of the above component (B) is less than 10 parts byweight per 100 parts by weight of the rubber component of the component(A), an effect for improving the reinforcing property and the otherphysical properties is less liable to be sufficiently exhibited. On theother hand, if it exceeds 100 parts by weight, it causes a reduction inthe processability. Considering the reinforcing property, the otherphysical properties and the processability, the blending amount of theabove component (B) falls particularly preferably in a range of 20 to 60parts by weight.

In the rubber composition of the present invention, when silica is usedas the reinforcing filer of the component (B), a silane coupling agentcan be blended for the purpose of further raising the reinforcingproperty. This silane coupling agent includes, for example,bis(3-triethoxysilylpropyl)tetrasulfide,bis(3-triethoxysilylpropyl)trisulfide,bis(3-triethoxysilylpropyl)disulfide,bis(2-triethoxysilylethyl)tetrasulfide,bis(3-trimethoxysilylpropyl)tetrasulfide,bis(2-trimethoxysilylethyl)tetrasulfide,3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane,2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane,3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,2-triethoxysilylethyl-N,N-dimethylthiocarbamonyl tetrasulfide,3-trimethoxysilylpropylbenzothiazole tetrasulfide,3-triethoxysilylpropylbenzothiazolyl tetrasulfide,3-triethoxysilylpropylmethacrylate monosulfide,3-trimethoxysilylpropylmethacrylate monosulfide,bis(3-diethoxymethylsilylpropyl) tetrasulfide,3-mercaptopropyldimethoxymethylsilane,dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide anddimethoxymethylsilylpropyl-benzothiazole tetrasulfide. Among them,bis(3-triethoxysilylpropyl)tetrasulfide and3-trimethoxysilylpropylbenzothiazolyl tetrasulfide are suited in termsof an effect for improving the reinforcing property. These silanecoupling agents may be used alone or in combination of two or more kindsthereof.

In the rubber composition of the present invention, the modified polymerin which a functional group having a high affinity to silica isintroduced into a molecular active site is used as the rubber component,and therefore a blending amount of the silane coupling agent can bereduced more than those of usual cases. The preferred blending amount ofthe silane coupling agent is varied according to the kind of the silanecoupling agent, and it is selected in a range of preferably 1 to 20% byweight based on the silica. If this amount is less than 1% by weight,the effect of the coupling agent is less liable to be sufficientlyexhibited. On the other hand, if it exceeds 20% by weight, a gelation inthe rubber component is likely to be brought about. The preferredblending amount of the above silane coupling agent falls in a range of 5to 15% by weight in terms of the effects of the coupling agent and aprevention in gelation.

Various chemicals usually used in the rubber industry, for example,vulcanizing agents, vulcanization-accelerating agents, process oils,antioxidants, scorch preventives, zinc oxide and stearic acid can beadded to the rubber composition of the present invention as long as theobjects of the present invention are not damaged.

The vulcanizing agent described above includes sulfur, and a use amountthereof is preferably 0.1 to 10.0 parts by weight, more preferably 1.0to 5.0 parts by weight in terms of sulfur per 100 parts by weight of therubber component. If it is less than 0.1 part by weight, the vulcanizedrubber is likely to be reduced in a rapture strength, an abrasionresistance and a low heat buidup property. On the other hand, it exceeds10.0 parts by weight, it causes a loss in the rubber elasticity.

The vulcanization-accelerating agent which can be used in the presentinvention shall not specifically be restricted, and capable of beinggiven are, for example, vulcanization-accelerating agents of abenzothiazole base such as M (2-mercaptobenzothiazole), DM(dibenzothiazyl disulfide), CZ (N-cyclohexyl-2-benzothiazylsulfenamide)and a guanidine base such as DPG (diphenylguanidine). A use amountthereof is preferably 0.1 to 5.0 parts by weight, more preferably 0.2 to3.0 parts by weight per 100 parts by weight of the rubber component.

The process oil which can be used in the rubber composition of thepresent invention includes, for example, a paraffin base, a naphthenebase and an aromatic base. The aromatic base is used for uses in whichthe tensile strength and the abrasion resistance are regarded asimportant, and the naphthene base or the paraffin base is used for usesin which the hysteresis loss and the low heat buildup characteristic areregarded as important. A use amount thereof is preferably 0 to 100 partsby weight per 100 parts by weight of the rubber component, and if itexceeds 100 parts by weight, a tensile strength and a low heat buildupproperty of the vulcanized rubber tend to be deteriorated.

The rubber composition of the present invention is obtained by kneadingby means of a kneading machine such as a roll and an internal mixer, andit is vulcanized after mold-processed and can be used for uses such asrubber vibration insulator, belts, hoses and other industrial productsas well as tire uses such as tire treads, under treads, side walls,carcass coating rubber, belt coating rubber, bead fillers, chafers andbead coating rubber. In particular, it can suitably be used as rubberfor tire treads.

The pneumatic tire of the present invention is used by a conventionalmethod using the rubber composition of the present invention. That is,the rubber composition of the present invention containing, ifnecessary, various chemicals in the manner described above is processedinto the respective members at a stage where the rubber composition isnot vulcanized, and they are stuck and molded by means of a tire moldingmachine by a conventional method, whereby a green tire is molded. Thisgreen tire is heated and pressed in a vulcanizing machine to obtain atire.

The pneumatic tire of the present invention obtained in the mannerdescribed above has a good low fuel consumption and is excellentparticularly in a rapture characteristic and an abrasion resistance, andin addition thereto, the above rubber composition has a goodprocessability, so that the productivity is excellent as well.

EXAMPLES

Next, the present invention will be described more specifically withreference to examples in the following. However the present invention isnot limited to the examples.

The physical properties of the polymer were measured by methodsdescribed below.

<<Physical Properties of Polymer:>>

A number average molecular weight (Mn) and a weight average molecularweight (Mw) of the polymer were measured by gel permeationchromatography (GPC: HLC-8020 manufactured by Toso Co., Ltd., column:GMH-XL (two serial columns) manufactured by Toso Co., Ltd.), and thedifferential refractive index (RI) was used to calculate them in termsof polystyrene with monodispersed polystyrene used as a standard.

A micro structure in a butadiene part of the polymer was determined byan infrared method (Molero method), and a styrene unit content in thepolymer was calculated from an integral ratio in a ¹H-NMR spectrum.

A Mooney viscosity of the polymer was measured at 100° C. by means of anRLM-01 type tester manufactured by Toyo Seiki Co., Ltd.

Further, the physical properties of the vulcanized rubber were measuredby the following methods, and a Mooney viscosity of the rubbercomposition was measured in the following manner.

<<Physical properties of vulcanized rubber:>>

(1) Low Heatbuildup Property

The tan δ (50° C.) was measured at a temperature of 50° C., a distortionof 5% and a frequency of 15 Hz by means of a viscoelasticity measuringapparatus (manufactured by Rheometrix Co., Ltd.). The smaller the tan δ(50° C.), the larger the low heat buildup property.

(2) Fracture Characteristic (Tensile Strength)

The tensile strength at break(T_(b)) was measured according to JISK6301-1955.

(3) Abrasion Resistance

A Lanborn type abrasion tester was used to measure the abrasion amountat a slip rate of 60% at a room temperature, and it was shown by anindex in terms of an abrasion resistance index, wherein an abrasionindex of a control was set to 100. The larger the index, the better theabrasion resistance.

<<Mooney viscosity of rubber composition:>>

The Mooney viscosity (ML_(1+4,)/130° C.) was measured at 130° C. basedon JIS K6300-1994.

The dried and refined raw materials were used for polymerization unlessotherwise described.

Comparative Production Example 1 Production of Non-modified Polymer

A pressure proof glass vessel of 800 ml which was dried and substitutedwith nitrogen was charged with 300 g of cyclohexane, 40 g of1,3-butadiene, 10 g of styrene and 0.34 millimole of2,2-ditetrahydrofurylpropane, and 0.38 millimole of n-butyllithium(BuLi) was added thereto, followed by carrying out polymerization at 50°C. for 1.5 hour. The polymerization conversion rate was almost 100%.

Then, 0.5 ml of an isopropanol 5 weight % solution of2,6-di-t-butyl-p-cresol (BHT) was further added to the polymerizationsystem to terminate the polymerization, and the product was dried by aconventional method to thereby obtain a polymer A. The analytical valuesof the polymer thus obtained are shown in Table 1.

Comparative Production Example 2 Production of One Stage-modifiedPolymer

A pressure proof glass vessel of 800 ml which was dried and substitutedwith nitrogen was charged with 300 g of cyclohexane, 40 g of1,3-butadiene, 10 g of styrene and 0.38 millimole of2,2-ditetrahydrofurylpropane, and 0.42 millimole of n-butyllithium(BuLi) was added thereto, followed by carrying out polymerization at 50°C. for 1.5 hour. The polymerization conversion rate was almost 100%.

Tetraethoxysilane 0.352 millimole was added to the polymerizationsystem, and then modification reaction was further carried out at 50° C.for 30 minutes. Thereafter, 0.5 ml of an isopropanol 5 weight % solutionof 2,6-di-t-butyl-p-cresol (BHT) was added to the polymerization systemto terminate the polymerization, and the product was dried by aconventional method to thereby obtain a polymer B. The analytical valuesof the polymer thus obtained are shown in Table 1.

Comparative Production Examples 3 to 7 Production of One Stage-modifiedPolymers

Polymer C to Polymer G were obtained in the same manner as inComparative Production Example 2, except that in Comparative ProductionExample 2, modifying agents of kinds shown in Table 1 were substitutedfor tetraethoxysilane which was a modifying agent. The analytical valuesof the respective polymers thus obtained are shown in Table 1.

Production Example 1 Production of Two Stage-modified Polymer

A pressure proof glass vessel of 800 ml which was dried and substitutedwith nitrogen was charged with 300 g of cyclohexane, 40 g of1,3-butadiene, 10 g of styrene and 0.38 millimole of2,2-ditetrahydrofurylpropane, and 0.42 millimole of n-butyllithium(BuLi) was added thereto, followed by carrying out polymerization at 50°C. for 1.5 hour. The polymerization conversion rate was almost 100%.

Tetraethoxysilane 0.38 millimole was added to the polymerization system,and then modification reaction of the first stage was further carriedout at 50° C. for 30 minutes. Thereafter, 0.38 millimole ofN-(3-triethoxysilylpropyl)-4,5-dihydroimidazole, 2.28 millimole of tinbis(2-ethylhexanoate) and 2.28 millimole of water were further added tothe polymerization system, and then modification reaction of the secondstage was carried out at 50° C. for 60 minutes. In this case, 0.5 ml ofan isopropanol 5 weight % solution of 2,6-di-t-butyl-p-cresol (BHT) wasadded to terminate the polymerization, and then the product was dried bya conventional method to thereby obtain a polymer H. The analyticalvalues of the polymer thus obtained are shown in Table 1.

Production Examples 2 to 14 Production of Two Stage-modified Polymers

Polymer I to Polymer U were obtained in the same manner as in ProductionExample 1, except that in Production Example 1, tetraethoxysilane and/orN-(3-triethoxysilylpropyl)-4,5-dihydroimidazole which were the modifyingagents were changed to modifying agents of kinds shown in Table 1. Theanalytical values of the polymers thus obtained are shown in Table 1.

Production Example 15 Production of Two Stage-modified Polymers

Polymer V was obtained in the same manner as in Production Example 1,except that in Production Example 1, titanium tetrakis(2-ethylhexyloxide) was substituted for tin bis(2-ethylhexanoate) which was acondensation-accelerating agent. The analytical values of the polymerthus obtained are shown in Table 1.

Production Example 16 Production of Two Stage-modified Polymers

Polymer W was obtained in the same manner as in Production Example 1,except that in Production Example 1, lithium hexamethyleneimide(hexamethyleneimide/Li mole ratio=0.9) of 0.42 millimole in terms oflithium equivalent which was prepared in the polymerization system wassubstituted for n-butyllithium which was a polymerization initiator. Theanalytical values of the polymers thus obtained are shown in Table 1.

Comparative Production Example 8 Production of one Stage-modifiedPolymer

Polymer X was obtained in the same manner as in Comparative ProductionExample 2, except that in Comparative Production Example 2, lithiumhexamethyleneimide (hexamethyleneimide/Li mole ratio=0.9) of 0.42millimole in terms of lithium equivalent which was prepared in thepolymerization system was substituted for n-butyllithium which was apolymerization initiator. The analytical values of the polymers thusobtained are shown in Table 1.

TABLE 1-1 Comparative Production Example 1 2 3 4 5 Kind of polymer A B CD E Polymerization initiator Kind BuLi BuLi BuLi BuLi BuLi Amount(mmole) 0.38 0.42 0.42 0.42 0.42 First stage Modifying Kind — TEOS TTCTEOSPDI DMBTESPA modification agent Amount (mmole) 0.352 0.352 0.3520.352 Second stage Modifying Kind — — — — — modification agent Amount(mmole) — — — — — Condensing Kind — — — — — agent Amount (mmole) — — — —— Characteristic Molecular Base Mw 23.0 20.8 21.5 20.1 19.0 weight(×10⁴) Total Mw 23.0 42.5 67.0 31.0 26.8 Micro Styrene unit 20.0 19.820.0 19.5 20.1 structure content (wt %) Vinyl group 57 57 56 58 54content Mooney viscosity (ML₁₊₄,/100° C.) 24 52 78 33 32

TABLE 1-2 Comparative Production Example Production Example 6 7 1 2 3Kind of polymer F G H I J Polymerization initiator Kind BuLi BuLi BuLiBuLi BuLi Amount (mmole) 0.42 0.42 0.42 0.42 0.42 First stage ModifyingKind GPMOS GPEOS TEOS TEOS TEOS modification agent Amount (mmole) 0.3520.352 0.38 0.38 0.38 Second stage Modifying Kind — — TEOSPDI DMBTESPAAPTES modification agent Amount (mmole) — — 0.38 0.38 0.38 CondensingKind — — BEHAS BEHAS BEHAS agent Amount (mmole) — — 2.28 2.28 2.28Characteristic Molecular Base Mw 20.4 20.6 21.0 20.6 20.2 weight (×10⁴)Total Mw 29.4 29.1 47.1 43.6 44.1 Micro Styrene unit 20.6 21.0 19.8 20.320.1 structure content (wt %) Vinyl group 55 58 56 57 57 content Mooneyviscosity (ML₁₊₄,/100° C.) 38 36 55 54 53

TABLE 1-3 Production Example 4 5 6 7 8 Kind of polymer K L M N OPolymerization initiator Kind BuLi BuLi BuLi BuLi BuLi Amount (mmole)0.42 0.42 0.42 0.42 0.42 First stage Modifying Kind TEOS TEOS TEOS TEOSTEOS modification agent Amount (mmole) 0.38 0.38 0.38 0.38 0.38 Secondstage Modifying Kind DMAPTMS MAPTMS HMTES OTMSAC APTMOS modificationagent Amount (mmole) 0.38 0.38 0.38 0.38 0.38 Condensing Kind BEHASBEHAS BEHAS BEHAS BEHAS agent Amount (mmole) 2.28 2.28 2.28 2.28 2.28Characteristic Molecular Base Mw 21.1 20.9 20.5 19.9 20.3 weight (×10⁴)Total Mw 43.1 41.8 45.6 42.8 44.6 Micro Styrene unit 19.8 19.9 19.5 20.619.5 structure content (wt %) Vinyl group 56 58 56 58 57 content Mooneyviscosity (ML₁₊₄,/100° C.) 53 54 53 55 54

TABLE 1-4 Production Example 9 10 11 12 13 Kind of polymer P Q R S TPolymerization initiator Kind BuLi BuLi BuLi BuLi BuLi Amount (mmole)0.42 0.42 0.42 0.42 0.42 First stage Modifying Kind TEOS TEOSPDI TEOSDMBTESPA GPMOS modification agent Amount (mmole) 0.38 0.38 0.38 0.380.38 Second stage Modifying Kind TMSEP TEOSPDI AEAPEOS TEOSPDI TEOSPDImodification agent Amount (mmole) 0.38 0.38 0.38 0.38 0.38 CondensingKind BEHAS BEHAS BEHAS BEHAS BEHAS agent Amount (mmole) 2.28 2.28 2.282.28 2.28 Characteristic Molecular Base Mw 20.7 21.0 20.0 20.5 21.0weight (×10⁴) Total Mw 45.1 33.7 41.6 28.0 31.4 Micro Styrene unit 20.220.4 20.0 20.0 20.1 structure content (wt %) Vinyl group 56 57 57 58 58content Mooney viscosity (ML₁₊₄,/100° C.) 55 38 51 39 40

TABLE 1-5 Comparative Production Production Example Example 14 15 16 8Kind of polymer U V W X Polymerization initiator Kind BuLi BuLi HMI HMIAmount (mmole) 0.42 0.42 0.42 0.42 First stage Modifying Kind GPEOS TEOSTEOS TEOS modification agent Amount (mmole) 0.38 0.38 0.38 0.352 Secondstage Modifying Kind TEOSPDI TEOSPDI TEOSPDI — modification agent Amount(mmole) 0.38 0.38 0.38 — Condensing Kind BEHAS TEHO BEHAS — agent Amount(mmole) 2.28 2.28 2.28 — Characteristic Molecular Base Mw 20.7 21.2 19.319.8 weight (×10⁴) Total Mw 30.5 45.0 42.7 40.9 Micro Styrene unit 19.720.6 20.2 19.8 structure content (wt %) Vinyl group 56 57 57 57 contentMooney viscosity (ML₁₊₄,/100° C.) 42 58 39 34Remarks:

-   Base Mw: weight-average molecular weight (Mw) before modification    reaction-   Total Mw: weight-average molecular weight (Mw) after first stage    modification reaction-   BEHAS: tin bis(2-ethylhexanoate)-   TEHO: titanium tetrakis(2-ethylhexyl oxide)-   HMI: hexamethyleneiminolithium synthesized in the polymerization    system-   TEOS: tetraethoxysilane-   TTC: tin tetrachloride-   TEOSPDI: N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole-   DMBTESPA: N-(1,3-dimethylbutylidene)-3-triethoxysilyl)-1-propane    amine-   GPMOS: 3-glycidoxypropyltrimethoxysilane-   GPEOS: 3-glycidoxypropyltriethoxysilane-   APTES: 3-aminopropyltriethoxysilane-   DMAPTMS: 3-(N,N-dimethylamino)propyltrimethoxysilane-   MAPTMS: 3-(N-methylamino)propyltrimethoxysilane-   HMTES: hydroxymethyltriethoxysilane-   OTMSAC: octadecyldimethyl(3-trimethoxysilylpropyl)-ammonium chloride-   APTMOS: aminophenyltrimethoxysilane-   TMSEP: 2-(trimethoxysilylethyl)pyridine-   AEAPEOS: 2-(6-aminoethyl)-3-aminopropyl-trimethoxysilane

Examples 1 to 16 and Comparative Examples 1 to 8

The polymers prepared in Production Examples 1 to 16 and ComparativeProduction Examples 1 to 8 were used to prepare silica-blended rubbercompositions and carbon black-blended rubber compositions according to acomposition 1 and a composition 2 each shown in Table 2 by methods shownbelow, and the rubber compositions were measured for a Mooney viscosityand then vulcanized on the conditions of 160° C. and 15 minutes. Thephysical properties of the vulcanized rubbers were measure, and theresults thereof are shown in Table 3.

Composition 1 Silica-blended:

Silica, aroma oil, stearic acid, a coupling agent and an antioxidant 6Cwere blended with 100 parts by weight of the polymer of a kind shown inTable 3 according to a composition 1 shown in Table 2 to prepare amaster batch, and zinc oxide, a vulcanization-accelerating agent DPG,DM, NS and sulfur were further blended to prepare a silica-blendedrubber composition.

Composition 2 Carbon Black-blended:

Carbon black, aroma oil, stearic acid, a coupling agent and theantioxidant 6C were blended with 100 parts by weight of the polymer of akind shown in Table 3 according to a composition 2 shown in Table 2 toprepare a master batch, and zinc oxide, the vulcanization-acceleratingagent DPG, DM, NS and sulfur were further blended to prepare a carbonblack-blended rubber composition.

TABLE 2 Composition 1 Composition 2 (part by weight) (part by weight)First Polymer 100 100 stage Carbon black — 50 Silica 55 — Aroma oil 1010 Stearic acid 2 2 Coupling agent 5.5 — Antioxidant 6C 1 1 Second Zincoxide 3 3 stage Vulcanization- DPG 1 0.5 accelerating DM 1 0.5 agent NS1 0.5 Sulfur 1.5 1.5Remarks:

-   Silica: ┌Nipsil AQ (brand name)┘ manufactured by Nippon Silica Ind.    Co., Ltd.-   Carbon black: ┌Seast KH (N339) (brand name)┘ manufactured by Tokai    Carbon Co., Ltd.-   Coupling agent: silane coupling agent ┌Si69 (brand name)┘    manufactured by Degussa Co., Ltd.,    bis(3-triethoxysilylpropyl)tetrasulfide-   Antioxidant 6C: N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-   Vulcanization-accelerating agent DPG:    -   diphenylquanidine-   Vulcanization-accelerating agent DM:    -   mercaptobenzothiazyl disulfide-   Vulcanization-accelerating agent NS:    -   N-t-butyl-2-benzothiazylsulfenamide

TABLE 3-1 Comparative Example 1 2 3 4 5 Kind of polymer A B C D ESilica-blended Mooney viscosity 58 63 62 62 69 rubber [ML₁₊₄,/130° C.]composition Tensile strength 18.5 19.8 18.6 22.5 21.8 [T_(b)] (MPa) Lowheat buildup 0.138 0.131 0.141 0.093 0.098 property [tan δ] Abrasionresistance 100 107 95 124 124 Carbon black- Mooney viscosity 52 59 63 6166 blended [ML₁₊₄,/130° C.] rubber Tensile strength 20.7 21.7 22.5 22.722.4 composition [T_(b)] (MPa) Low heat buildup 0.151 0.145 0.127 0.1220.124 property [tan δ] Abrasion resistance 100 102 110 117 115(The abrasion resistance is a value shown by an index, wherein the valueof Comparative Example 1 was set to 100)

TABLE 3-2 Comparative Example Example 6 7 1 2 3 Kind of polymer F G H IJ Silica-blended Mooney viscosity 64 63 66 71 65 rubber [ML₁₊₄,/130° C.]composition Tensile strength 20.4 20.6 22.4 22 22.3 [T_(b)] (MPa) Lowheat buildup 0.125 0.127 0.081 0.085 0.084 property [tan δ] Abrasionresistance 110 108 136 133 130 Carbon black- Mooney viscosity 60 58 6468 62 blended [ML₁₊₄,/130° C.] rubber Tensile strength 21.4 21.6 22.9 2322.6 composition [T_(b)] (MPa) Low heat buildup 0.141 0.143 0.108 0.1110.113 property [tan δ] Abrasion resistance 103 102 127 125 124(The abrasion resistance is a value shown by an index, wherein the valueof Comparative Example 1 was set to 100)

TABLE 3-3 Example 4 5 6 7 8 Kind of polymer K L M N O Silica-blendedMooney viscosity 62 63 66 67 64 rubber [ML₁₊₄,/130° C.] compositionTensile strength 21.9 22.4 22.2 22.5 22.6 [T_(b)] (MPa) Low heat buildup0.089 0.086 0.088 0.083 0.088 property [tan δ] Abrasion resistance 127129 132 128 128 Carbon black- Mooney viscosity 60 61 — 63 64 blended[ML₁₊₄,/130° C.] rubber Tensile strength 22.7 22.5 — 22.4 22.3composition [T_(b)] (MPa) Low heat buildup 0.118 0.115 — 0.114 0.116property [tan δ] Abrasion resistance 121 123 — 122 123(The abrasion resistance is a value shown by an index, wherein the valueof Comparative Example 1 was set to 100)

TABLE 3-4 Example 9 10 11 12 13 Kind of polymer P Q R S T Silica-blendedMooney viscosity 68 70 72 74 71 rubber [ML₁₊₄,/130° C.] compositionTensile strength 21.9 22.6 22.3 22.3 22.7 [T_(b)] (MPa) Low heat buildup0.083 0.076 0.085 0.080 0.079 property [tan δ] Abrasion resistance 132140 132 136 138 Carbon black- Mooney viscosity 63 68 67 70 67 blended[ML₁₊₄,/130° C.] rubber Tensile strength 22.6 23.1 22.6 22.9 23.2composition [T_(b)] (MPa) Low heat buildup 0.113 0.103 0.109 0.107 0.106property [tan δ] Abrasion resistance 124 131 122 128 128(The abrasion resistance is a value shown by an index, wherein the valueof Comparative Example 1 was set to 100)

TABLE 3-5 Comparative Example Example 14 15 16 8 Kind of polymer U V W XSilica-blended Mooney viscosity 70 69 72 68 rubber [ML₁₊₄,/130° C.]composition Tensile strength 22.5 21.9 22.7 23.1 [T_(b)] (MPa) Low heatbuildup 0.081 0.085 0.071 0.089 property [tan δ] Abrasion resistance 137132 144 125 Carbon black- Mooney viscosity 69 68 70 68 blended[ML₁₊₄,/130° C.] rubber Tensile strength 22.7 22.7 23.5 23.0 composition[T_(b)] (MPa) Low heat buildup 0.108 0.111 0.098 0.117 property [tan δ]Abrasion resistance 126 123 134 120(The abrasion resistance is a value shown by an index, wherein the valueof Comparative Example 1 was set to 100)

It can be found from the results described above that the modifiedpolymers of the present invention (Examples 1 to 16) inhibit a rise inthe Mooney viscosity and markedly raise the low heating property and theabrasion resistance without damaging the fracture characteristic ineither case of silica blending and carbon black blending.

INDUSTRIAL APPLICABILITY

According to the present invention, capable of being provided is amodified polymer which enhances interactions with silica and carbonblack when used for both of silica-blended and carbon black-blendedrubber compositions and which elevates the fracture characteristic, theabrasion resistance and the low heat buildup property at the same timeand can exhibit a good workability.

1. A process for producing a modified polymer, characterized by carryingout primary modification in which a hydrocarbyloxysilane compound I isreacted with the active site of a polymer having an active site of anorganic metal in a molecule and then carrying out secondary modificationin which the hydrocarbyloxysilane compound II or unreactedhydrocarbyloxysilane compound I is further reacted therewith.
 2. Theprocess for producing a modified polymer as described in claim 1,wherein the polymer described above is obtained by homopolymerizing aconjugated diene compound or copolymerizing a conjugated diene compoundwith at least one other monomers.
 3. The process for producing amodified polymer as described in claim 1, wherein the organic metal inthe active site of a polymer is at least one selected from an alkalinemetal and an alkaline earth metals.
 4. The process for producing amodified polymer as described in claim 2, wherein the polymer issynthesized by anionic polymerization, and the at least one othermonomer is an aromatic vinyl compound.
 5. The process for producing amodified polymer as described in claim 4, wherein the active sitedescribed above is present at an end of the polymer, and at least a partthereof stays in an active state.
 6. The process for producing amodified polymer as described in claim 1, wherein thehydrocarbyloxysilane compound I used for the primary modification is atleast one selected from a hydrocarbyloxysilane compound represented byFormula (I):

(wherein A¹ represents a monovalent group having at least one functionalgroup selected from (thio)epoxy, (thio)isocyanate, (thio)ketone,(thio)aldehyde, cyan, pyridine, imine, amide, trihidorocarbyl ester ofisocyanuric acid, (thio)carboxylic acid ester, metal salts of(thio)carboxylic acid ester, carboxylic anhydride, carboxylic halidesand dihydrocarbyl ester carbonate; R¹ represents a single bond or adivalent inert hydrocarbon group; R² and R³ each represent independentlya monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms ora monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms; nis an integer of 0 to 2, and when a plurality of OR³ is present, aplurality of OR³ may be the same as or different from each other; and anactive proton and an onium salt are not contained in the molecule)and/or a partially condensed product thereof, a hydrocarbyloxysilanecompound represented by Formula (II):

(wherein A² represents a monovalent group having at least one functionalgroup selected from cyclic tertiary amine, non-cyclic tertiary amine,pyridine, cyan, sulfide and multisulfide; R⁴ represents a single bond ora divalent inert hydrocarbon group; R⁵ and R⁶ each representindependently a monovalent aliphatic hydrocarbon group having 1 to 20carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18carbon atoms; m is an integer of 0 to 2, and when a plurality of OR⁶ ispresent, a plurality of OR⁶ may be the same as or different from eachother; and an active proton and an onium salt are not contained in themolecule) and/or a partially condensed product thereof, and ahydrocarbyloxysilane compound represented by Formula (III):R⁷ _(p)—Si—(OR⁸)_(4-p)  (III) (wherein R⁷ and R⁸ each representindependently a monovalent aliphatic hydrocarbon group having 1 to 20carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18carbon atoms; p is an integer of 0 to 2, and when a plurality of OR⁸ ispresent, a plurality of OR⁸ may be the same as or different from eachother; and an active proton and an onium salt are not contained in themolecule) and/or a partially condensed product thereof.
 7. The processfor producing a modified polymer as described in claim 6, wherein thehydrocarbyloxysilane compound II used for the secondary modification isat least one selected from the hydrocarbyloxysilane compound representedby Formula (I) described above and/or the partially condensed productthereof, the hydrocarbyloxysilane compound represented by Formula (II)described above and/or the partially condensed product thereof and ahydrocarbyloxysilane compound represented by Formula (IV):

(wherein A³ represents a monovalent group having at least one functionalgroup selected from alcohol, thiol, amide, primary amine or an oniumsalt thereof, cyclic secondary amine or an onium salt thereof,non-cyclic secondary amine or an onium salt thereof, cyclic tertiaryamine or an onium salt thereof, non-cyclic tertiary amine or an oniumsalt thereof, a group having an aryl or benzyl Sn bond, sulfonyl,sulfinyl and nitrile; R⁹ represents a single bond or a divalent inerthydrocarbon group; R¹⁰ and R¹¹ each represent independently a monovalentaliphatic hydrocarbon group having 1 to 20 carbon atoms or a monovalentaromatic hydrocarbon group having 6 to 18 carbon atoms; q is an integerof 0 to 2, and when a plurality of OR¹¹ is present, a plurality of OR¹¹may be the same as or different from each other) and/or a partiallycondensed product thereof.
 8. The process for producing a modifiedpolymer as described in claim 6, wherein the hydrocarbyloxysilanecompound I for the primary modification is added to the polymer havingan active site of an organic metal and reacted to introduce thehydrocarbyloxysilane compound residue into the above active site, andthen the hydrocarbyloxysilane compound II for the secondary modificationis added to the reaction system and condensed with thehydrocarbyloxysilane compound residue introduced into the active site.9. The process for producing a modified polymer as described in claim 6,wherein the hydrocarbyloxysilane compound I for the primary modificationis added to the polymer having an active site of an organic metal andreacted to introduce the hydrocarbyloxysilane compound residue into theabove active site, and then the secondary modification is carried out inwhich the unreacted hydrocarbyloxysilane compound I is condensed withthe hydrocarbyloxysilane compound residue introduced into the activesite.
 10. The process for producing a modified polymer as described inclaim 1, wherein a condensation-accelerating agent is added to thereaction system in the secondary modification.
 11. The process forproducing a modified polymer as described in claim 10, wherein thecondensation-accelerating agent is a combination of carboxylate of tinand/or titanium alkoxide and water.
 12. The process for producing amodified polymer as described in claim 11, wherein the carboxylate oftin is a tin compound having an oxidation number of 2 represented by thefollowing Formula (V):Sn(OCOR¹²)₂  (V) (wherein R¹² represents an alkyl group having 2 to 19carbon atoms) or a tin compound having an oxidation number of 4represented by the following Formula (VI):R¹³ _(x)SnA⁴ _(y)B¹ _(4-y-x)  (VI) (wherein R¹³ represents an aliphatichydrocarbon group having 1 to 30 carbon atoms; x is an integer of 1 to3, and y is 1 or 2; and A⁴ represents a group selected from a carboxylgroup having 2 to 30 carbon atoms, an α,γ-dionyl group having 5 to 20carbon atoms, a hydrocarbyloxy group having 3 to 20 carbon atoms and asiloxy group which is tri-substitute with a hydrocarbyl group having 1to 20 carbon atoms and/or a hydrocarbyloxy group having 1 to 20 carbonatoms; B¹ is represents hydroxyl group or halogen atoms), and thetitanium alkoxide described above is a titanium compound represented bythe following Formula (VII):A⁵ _(z)TiB² _(4-z)  (VII) (wherein A⁵ represents a group selected froman alkoxy group having 3 to 20 carbon atoms and a siloxy group which istri-substitute with an alkyl group having 1 to 20 carbon atoms and/or analkoxy group having 1 to 20 carbon atoms; B² represents an α,γ-dionylgroup having 5 to 20 carbon atoms; and z is 2 or 4).
 13. The process forproducing a modified polymer as described in claim 2, wherein theconjugated diene compound described above is 1,3-butadiene or isoprene.14. The process for producing a modified polymer as described in claim4, wherein the aromatic vinyl compound is styrene.